Mold



Feb. 6, 1945. E, MAYER 2,369,067

MOLD

Filed April 8, 1941 7 Sheets-Sheet l In veni'or:

Feb. 6, 1945. MAYER: 2,369,067

MOLD A Filed April 8, 1941 7 Sheets-Sheet 2 Inventor:

6, 1945. r E, MAYER 2,369,067

MOLD

Filed April 8, 1941 7 Sheets-Sheet 3 $2 In vento r:

' mm 2/ W Feb. 6, 1945. MAYER 2,369,067

' MOLD Filed April 8, 1941 7 Sheets-Sheet 4 79 20 Inventor;

Feb. 6, 1945 E. MAYER MOLD Filed April 8, 1941 7 Sheets-Shee t 5 Feb. 6,1945. 5 MAYER 2,369,067 MOLD Filed April 8, 1941 7 Sheets-Sheet 6 lnventar:

5-. MAYER Feb. 6, 1945.

MOLD

Filed April 8, 1941;

7 Sheets-Sheet Inventor:

Patented Feb. 6, 1945 MOLD Ernest Mayer, Leipzig, Germany; vested in the Q Alien Property Custodian Application April 8, 1941, Serial No. 387,531. 7

In Germany November 25, 1939' 16 Claims.

This invention relates to a mold for air-cooled ribbed cylinders, cylinder heads, or similar ribbed work.

It has been the prevailing practice hitherto to cast objects of this class in two-part molds produced with the aid of patterns. The production of such molds is, however, quite bothersome, protracted and. difficult and requires a skilled molder. Furthermore, as the narrow gaps between the ribs of the pattern prohibit tamping down of the ,molding sand the latter must 'be loosely thrown in. and the riblike mold parts have to be fitted with a large number of pins which often get out of line and have to be knocked out during cleaning whereby the casting may be damaged. The use of an ordinary mold involves, moreover, the drawback that a cylinder cast therein has a seam running around it and its appearance is as a rule not satisfactory. The half ribs are usually displaced relative to each other at the seams, and the casting is seldom accurate to size, because the pattern cannot be smoothly removed from the mold, particularly if the ribs are closely arranged and possess a slight wall thickness to insure elfective cooling. Special difficulties have also to be overcome at present in cleaning a casting fitted with closely adjacent thin ribs whichbreak off easily, so that relatively much waste occurs. The necessity of gettin the pattern out of the mold restricts the possibilities of shaping the part to be cast, and for this reason the shape and arrangement most favorable for instance to cooling must often be sacrificed.

It is known to employ in the casting of cylinder heads provided with cooling ribs and intended for air-cooled engines a mold builtup from supertapering off towards the outer edge, and during the removal of the plates, which must be done while the castin is still semiplastic, either the ribs or the casting is easily damaged.

Compared with the known art, the invention resides in providing for a mold of the type mentioned comprising flat superposed plates of which two adjacent ones form the mold part corresand as undivided plates in consequence whereof the casting can shrink without impediments and has no seam. Apart from the very simple rib patterns required for the production of the core plates, no pattern for the casting is needed and the drawbacks connected with casting to pattern are eliminated. As the cores drop out by themselves and smooth surfaces are obtained, Cleaning is greatly facilitated and often superfluous. Any desired shape may furthermore be imparted to the rib and casting, which is particularly suited for cooling, such as a cruciform, wavelike, etc., shape. The production of the mold requires only a few simple core boxes, core pins can be dispensed with entirely and in. producing the mold parts limiting the hollow ribspaces the sand may be stamped in the usual manner. There is moreover no seam, since the parting lines coincide with the edges of the ribs. The manufacture of the mold is considerably speeded up, because the platelike core members can be produced by unskilled female operators and the building up of the mold from the plates does not offer any difiiculties.

The platelike construction of the mold for an air-cooled engine cylinder or cylinder head providesmoreover surprising possibilities for shapin the cooling ribs in an advantageous manner. For example, the ribs may be provided with reinforcing connecting flanges which may be formed also of metal bars inserted in the core plates.

Other advantages afforded by a mold according to the invention comprise the saving eifected in sand and the elimination of molding pins. The invention further permits the manufacture of the core plates from iron borings or from a mixture of iron borings and sand instead of from pure sand so as to vary at will the hardness, grain and smoothness of the casting. If the core plates are made entirely from iron borings the cast material will resemble a chilled casting.

According to theinvention the sand core plates are further inserted in iron or metal holding means or produced in annular or platelik iron or metal holders whose outer circumference exactly corresponds to the hollow section of the molding box. The metal plates, which may be repeatedly usedjinsure good fitting and accurate guiding of the core plates in the molding box as Well as the proper thickness of the latter, of the hollow molds :tor the ribs and of the ribs of'the casting to be made.

In numerous instances the sand cor'e plates each of which is set in a metal platemay be used spending to a-rib core members produced in the *withoutmolding boxes, in which case the metal The invention makes it possible to cast two or i more cylinders on top of each other in a single; molding box and thereby to save an upper and a lower core which serve forholding'the gate and the core for the bore. I

The mold according to the invention ma limited by two core plates 3 are provided with inserted flat annular plates 9 whose outline ands cross-sectional form .exactly correspond to the shape of the ribs of the casting and which possess at their inner edge a projection III of dovetailed cross section, which-extends into the hollow space I I of the mold intended for forming the cylinder wall. During the casting operation the projections; III are embeddedv in, or welded to, the cast metal of the cylinder wall.

The mold shown in Fig. 5 serves for a cylinder head having differently formed ribs in planes extending vertically to the cylinder axis and paral- V lel to this axis, and comprises a molding box I2 shown undivided in Fig. 5, though it may be made upalso of two or more parts united by screws.

' In the. box. t2. sand cores I3 for forming the holused also for connecting by casting the. ribs made by a separate process with the cylinder liner cast in the mold. To this end the ribs are inserted in the" hollow? spaces. formed; by'two adjacent: core plates in; such. manner: that. the: inner edges projecti'nto the hollow mold space serving for forming. theliner-andaduring; pouring of themetal are surrounded thereby- The mold may be. employed also for casting: the: ribs around a finished liner to which they are secured by shrinking during cooling of the metal, the liner being inserted as core in the mold.

Other objects of: the. invention; refer to details of" construction, arrangement and production. of the; core plates limiting the: hollow rib spaces, and to the eflects resulting. therefrom, as described in'the specification.

Theinvention is illustrated by way. of example intheaccompanying drawings; inwhich Figures I and 2' showra cylinderrmold according to the inventiom. Fig; 1-. being a vertical partial section its the direction; of the cylinder axis and Fig- 2 WCIZOSSKSECHOH on. the line- 2-4, of. Fig.1;

Figs. EL and 4' show a mold: according to the invention: with inserted metal ribs,v Fig... 3 being a" partial section through the: cylinder axis: and Fig. 4 a cross section on the line 4-4, of Fig. 3;

Fig; El-

an axial section of a mold for: casting a cylinder head; and

Figs. 6 to; 1.7 are detail. views; partly: in. elevation and partly in section, of? the: construction and arrangement: of coraplates;

Figs; 1 to. show a mold; in which in; a. cylindricak molding. box I anumher of plateli'ke core members '3' are: superposed ona. core 2'. The core members 3 are each. made; from sand in an annular metal plate 8' and withv the air: of. these plates whose circumferential shape is accurately adapted to the hollow' section of the box. I. inserted in: the latter; To: prevent turning the core plates 3 possess atone point. of their circumferencea fiat portion 4 corresponding to a ledgelike axially'parallel reinforcement 5:- on the inside of the box I, which has the same cross-sectional form as the fiat.- pontions 01- they plates, whose inner edge; and side: faces are so" constructed that two adjacent platesi always; limit: a hollow space 6 required ior' forming a. casting rib, as indicatedin Fig. 1.

At a slight: distance from: their outer edge the hollow spaces 6 are connected;- by openings. I of the. core plates 3,, which serve for forming: the

connecting andreiniorcing members between the low spaces for the casing receiving the valve conoi said plates always. forming the. hollow molds I5 for the axially parallel extending cooling ribs. Each sand core plate I4 is firmly united with a metal plate. I6 whose outline coincides; with that of the alining means ofthe box I2 and whose thickness generally corresponds. to the thickness of: the castv rib on theouter edge thereof.

Asindicated in Figs. 6 and 7, the sand core plates M are produced. on a. flat. side of the metal plate.- I6. The: sand core. isfirmly connected with the metal plate I6 by means of openings I-I, I8 which are formed inthe plate and may also be undercut. to insure better anchoring of the sand, and. of undercut. projections I9 on the. flat side where the sand core plate is. formed, whose height together with the thickness oiv the plate I6 is equal to the spacing of the ribs plus the thickness thereof. The portion of the sand corev plate I4 freely projecting. beyond the inner edge of the metal plate I6: is preferably reinforced by radially disposed small' metal plates 20 whose ends overlap. the plate. I6 and are. provided with openings. 2 l and edge clearances 22.

For; making the sand core plate I4.,a pattern is used comprising 'a. base plate; which, is. flat as a ruleand on which. the rib pattern is secured. The base. platev is fitted with alining. stops for arranging thereon and, 'alining. the metal plate I6 which is, placed on the base plate. In the mold thus formed the. corev plate is produced in known. manner from white core sand with the aid of. a plate or if necessary of a second pattern molding the top side of the core plate and after separation from the pattern united with the metalplate I6.

As indicated by dashes and dots, Figs. 6 and I, the sand core; parts. projecting from the metal plate [6 can be. supported relativeto one another after assembling in the mold by means of projections 23 of rib thickness which are positioned on the sides. thereof and, produce holes in the cast ribs, The provisionof projections 23 for supporting the projecting portions of the sand core plates I4 in. thev mold makes it possible in some instances to dispense.- with the. metal insertions 2.0; I

The. pairs of core plates. [4, I 6.- between the. sand cores- I3 have the. same shape and are symmetrically arranged on both sides of a central rib. or of a hollow mold serving tor forming it, whose thickness and form. of edge. are determined bya. steelv plate: 2.4. inserted between the two adjoining core plates. i I

0n thecnres l3. or on the receiving ledges or the surface of the molding box another set of core plates 21 is piled which form the hollow molds 28 of ribs extending in planes disposed vertically to the cylinder axis. On alining pins 29 inserted in a flange so of the molding box |2 the core plates 2! are placed with the openings provided in their metal plates 3|, 3|", and on the plates 27 a plate 32 is put which receives the mold top, not shown, holds the core 33 for the bore and is fitted with the usual gate and risers.

The metal plates 3|, 3| are so arranged in pairs Within one another that the lower plate 3| of each pair possesses on the outer edge an upwardly directed annular projection 3|, and in the flat depression thus formed on the upper side of the plate 3! the other plate 3| is inserted. As the height of the projection 3| of the plate 3| is somewhat less than the thickness of the inserted plate 3|, a small interstice through which gas and air can escape from the core plates exists between the top of the projection 3| and the underside of the next plateffitted with a projection. Otherwise, the core plates composed of the metal plates 3|, 3| and the sand cores 2'! are similarly arranged. and produced as the previously described core plates 'made up from the metal plates l6 and the sand .core plates 4 which are positioned parallel 'to the cylinder axis. The joining of the metal plates 3|, 3| in pairs is advisable when the ribs have a small wall thickness and are slightly spaced to prevent distortion and deformation of the core plates wherebythe accuracy to size of the casting would be afiected. The arrangement described protects both plates, one by reinforcement of the edge and the other by being inserted in the first, against deformation, 1

In the construction shown in Figs. 8 and 9 the sand cores 34 are anchored in their metal plates 35 by means of a groove 35 and of additional clearances 31 provided on the inner edge of the metal plates and fitted with reinforcements in the form of thin perforated metal plates. In the embodiment shown these reinforcements are constructed as ring sector plates 38 which when disposed on an outer side of the platelike sand cores 34 serve also for chilling the cast metal.

The construction of the core plate shown in Figs. and 11 difiers from'the, one just described only in so far as the reinforcements 39 are arranged so as to reinforce the inner edge of the sand core plate.

Further reinforcement of the thin-walled core plate is attained according to the invention by coating the finished and baked plate with linseed oil, dextrine, a sugar solution, colophony or similar hardenable substances.

To insure accuracy to size of the casting in axial direction in spite of any possible deformation or wear of the metal plates during assembling of the mold from the various core plates, which is particularly important in case of cylinders for two-cycle engines, cylinder heads for air-cooled aircraft engines and all work pieces having control ports whose openings must be placed on an accurately determined level, the superposed core plates, it metal holding plates of less thickness thancorresponds to the spacing plus thickness of the ribs are employed are relieved from the pressure produced by the assembling of the core plates by means of compression bars inserted in registering bores of the core plates. This varrangement is illustrated in Figs. 12 and 13 which show a core plate for an air-cooled two-cycle engine cylinder and a section through a number of superposed plates on the line |3|3, of Fig. 12. The metal holding plate 40 of the sand core plate 4| possesses a closed bore 42 and an edge clearance 43 for alining the core plates relative to one another. By inserting a rod in the clearances 43 subsequent alining of the plates is possible, so that in the building up of the mold the plates can be relatively displaced as required for the insertion of the cores. The metal plate 40 has four bores 44 which are in register in the superposed core plates after alinement. During construction of the mold, cylindrical members 45, Fig. 13,

- whose height is exactly like the spacing plus thickness of the ribs are inserted in the bores 44. In the finished mold the superposed members 45 form continuous compression bars or struts which relieve the core plates of the weight of the top and insure accuracy to size of the casting in axial direction. When the core plates are produced and used without metal holders, their openings 44 are preferably reinforced by inserted sleeves which may directly serve as spacing means 45. The bores 42 and the clearances 43 are also suitably provided with a metal lining.

The core plates shown in Figs. 14 to 17 differ from those described in that for the purpose of establishing a firmer union of the sandportion and the metal portion the edges of the metal plate connecting with the sand portion are fitted with pins whose projecting parts are embedded in the platelike sand core. In the core plate shown in Figs. 14 and 15 andserving for forming the hollow mold for a short ribbed piece of the kind used at the upper part of a cylinder head, Fig. 5, the metal plate 46 hasa rectangular outer edge corresponding to the form of the molding box in which it is inserted. The inner edge has a polygonal formcorresponding to the outer edge 41 of the rib 48 whcih-is to be molded thereby. Into a side face of the metal plate 46 fiat grooves 49 are out which extend from the inner to the outer edge and serve for discharging air and gas from the sand mold. The polygonal inner edge of the metal plate 46 is undercut on both sides to clamp the edge of the sand core plate 53 to the metal plate. The edges 50, 5| of the plate 4|iare bevelled so that the slope corresponds to the. counter-templet.

The metal plates 46 are provided on their inner edge where the sand core plate 53 is connected with pins 52 partly projecting from the plates parallel with the sides thereof. The pins 52 are spaced approximately 20 mm:, though this distance is preferably decreasing toward the outside in the plate shown in Fig. 14. When the holes for the pins 52 have to be drilled obliquely in places that are difiicultly accessible, the projecting portions thereof are bent ofi-into the plane of the plate.

The sand core 53 connected with the pins 52 has the same thickness as the metal plate 46 from the point adjoining the inner edge of the metal plate up to the outer limiting line of the hollow rib space where the real core 48 connects which fills the space between the two ribs. The portion of the core plate made of sand is reinforced by armori'ng insertions. In the construction shown in Figs. 16, 17 the annular metal plate 54 having a thickness equal to the spacing plusv thickness of theribs is provided on the inner edge with pins 55 spaced about 20 mm. whose ends project approximately 5 mm. parallel with the side. faces of the plate and are embedded in the sand core during connection of the sand core plate, m

Fig. 1'7 shows the bending of the projecting pin portions into the plane of the annular plate when the holes in which the pins are inserted are drilled tions, metal frames of no greater thickness than the outer parts of the core plates and having parallel upper and lower faces, said outer parts of the'core platesbeing in superposed contact, and means for alining and fixing the metal frames relative to one another.

2. A mold according to claim 1, in which the thin-walled sand core parts are reinforced by platelike metal insertions.

3. A mold according to claim 1, inwhich the thin-walled sand coreparts are reinforced by platelikeperforated metal insertions.

4. A mold according to claim 1, in which the thin-walled sand core parts are reinforced by platelike metal insertions'having a shape adapted to the form of the ribs and arrangedto act as chilling means.

' 5-. A mold according to claim 1, in which the .sand core plates are apertured.

6. A mold according to claim 1, in which the sand core plates are apertured and metal rods are inserted in the apertures.

7. A mold accordingto claim 1, in which the sand core plates are inserted in a molding box and both the core plates and the molding box are provided with means for alining and fixing the core plates.

8.,A mold according "to claim 1, in which'the sand core plates are heldin metal plates.

9. A mold according to claim 1, in which the sand core plates are held in metal plates and the metal holders are provided with means for alining and fixing another.

10. A mold according to claim 1, inwhich the sand core plates are held in metal plates and the metal holding plates are arranged in pairs in one another, so that oneplate is reinforced at its outer'edge by a projection and the other metal plate is inserted in the depression formed thereby.

11. A mold according to claim 1, in whichthe sand core plates are held'in metal plates and means for relieving the core plates of pressure are provided. I j e m 12;"A mold according to claim 1, in which the sand core plates are held in metal plates and the plates carrying the sand cores are so formed that their inner edges limit the rib mold, 13. A mold according to claim 1, in which the sand core plates are held in metal plates having approximately the thickness of a, cast rib and undercut openings and/ or projections for anchorembracing the sand cores, the metal frames being ing the'molding sand. I 15. A mold according to claim 1, in which the sand core plates are connected with vmetal plates and the core plate comprising a sand portion and a metal portion has a thickness equal to the spacingof the ribs plus the thickness of a rib.

16. A mold for ribbed work pieces, comprising core plates of sand, metal frames supporting and in superposed contact, the adjacent sand core plates being spaced to provide a cast rib on the work pieces.

' ERNEST MAYER.

the core plates relative to one 

